1. Field of the Invention
The present invention relates to a push-on connector used as an optical connector or a coaxial cable connector.
2. Prior Art Description
The assignee of the present invention had proposed a locking construction of such a connector in a Japanese utility model application No. 21,277/87 dated Feb. 18, 1987 (opened No. 164,183/88 opened on Oct. 26, 1988).
FIGS. 1 and 2 of the published utility model show the prior art connector namely push-on connector having the locking construction.
In order to help a better understanding of the present invention, the prior art will be explained at first. FIG. 1 shows in general the locking construction of the connector of the utility model. In FIG. 1, A indicates an adaptor or female connector and B indicates a plug or male connector to be inserted and mated with the adaptor A. Between a coupling 7 and a connector body of the plug B, a slide ring 10 is provided. The diameter of the slide ring 10 is so selected to abut against a stopper 2 provided in the adapter A on its entire periphery or divided into a plural number. The FIGURE shows a case of providing the stopper 2 on the entire periphery of the adaptor A. Furthermore, a spring member 11 is provided between the slide ring 10 and the body 3 by which spring member 11 the slide ring 10 is depressed or biased towards the direction of the adapter A. Also at the inner periphery of the coupling 7, a stopper ring 12 is provided. A stopper 13 is provided around the outer periphery of the slide ring 10 to engage with the stopper ring 12 and by which the outer extreme position of the slide ring 10 is limited. By this arrangement, the slide ring 10 normally occupies a position to cover an engaging reentrant portion 4. In FIG. 1, 14 of the plug B shows a ferrule to hold an optical cable at its center and 1a of the adapter A shows an axial slit provided in the body 1 and 15 is a slit sleeve and 16 is a stopper.
In the above construction of the connector, when the plug B is inserted into the adapter A by holding the coupling 7, the stopper 2 of the adapter A depresses the front end surface of the slide ring 10 against the spring force of the coil spring member 11. The slide ring 10 moves backward towards the holding portion 8 of the cable 9 as can be seen from FIG. 2a so that the stopper 2 of the adapter A falls into the engaging reentrant portion 4 as can be seen from FIG. 2b. Then the slide ring 10 restores its original position by the bias force of the coil spring 11 and covers outer periphery of the stopper 2 engaging by dropping into the engaging reentrant portion 4 so as to prevent disengagement of the connectors and thus the connection and locking motion is completed. At dislocking the connector and its connection, contrary to the above operation the coupling 7 is pulled backwardly. Then the stopper ring 12 of the coupling 7 presses the stopper 13 of the slide ring 10 against the bias force of the spring 11 towards the holding portion 8 of the cable 9 to expose the engaging reentrant 4. By the further pulling force applied to the coupling 7, the stopper 2 of the receptacle A is disengaged from the engaging reentrant 4 so that the connectors are uncoupled and the connection is broken at the same time.
This kind of the connector provided with the locking construction can be handled easily for its two kind of operations i.e. locking and connecting by holding only the coupling 7 so that it has an advantage of simple handling in a single operation to avoid a double operation. However, during actual use thereafter it has shown up points still to be solved and improved.
At the disengagement motion of the locked connector in the above locking construction, as has been explained, the coupling 7 is pulled backwards and by this pulling force, the slide ring 12 is retracted against the bias force of the coil spring 11 towards the holding portion 8 and by a further pulling force the stopper 2 disengages from the engaging reentrant portion 4 to dislock the locked connector. At this time, all the dislocking force is conveyed to various portion of the connector via the spring 11.
In other words, all the dislocking force is loaded to the spring 11 so that after a number of coupling and uncoupling operations of the connector, the spring 11 may have a permanent deformation and the bias force to be applied to the stopper 13 is decreased gradually. This phenomenon is so-called "fatigue of spring".
This fatigue of spring can be avoided by selecting the spring member within a certain condition. But by the recent requirement of miniaturization of connectors, the space accommodating the spring member is narrowly limited thus the selection of the spring becomes more and more difficult.